Method and apparatus for installing elongated rods in unstable earth formations

ABSTRACT

The method and apparatus are an improvement on the patentee&#39;&#39;s earlier method and apparatus for installing an elongated rod in an earth formation by the steps of installing a tubular casing in a tunnel in a face of the formation, inserting the rod in the casing, and then retracting the casing from the tunnel. According to the new method, they install and retract the casing through a liquid seal adjacent the face of the formation, and charge a liquid medium into the tunnel through the seal to pressurize the tunnel about the casing, and to retain the formation about the rod when the casing is retracted from the tunnel.

United States Patent Sweeney et al.

[54] METHOD AND APPARATUS FOR INSTALLING ELONGATED RODS IN UNSTABLEEARTH FORMATIONS [72] Inventors: Gerald T. Sweeney; Oliver E. Erdman,

UNITED STATES PATENTS Lawton ..61/53.68 X

Lagerstrom ..61/53.64 X

Sweeney et a1. .1 ..6l/53.68 X

Primary Examiner-Dennis L. Taylor Attorney-Christensen & Sanborn [57]ABSTRACT The method and apparatus are an improvement on the patenteesearlier method and apparatus for installing an elongated rod in an earthformation by the steps of installing a tubular casing in a tunnel in aface of the formation, inserting the rod in the casing, and thenretracting the casing from the tunnel. According to the new method, theyinstall and retract the casing through a liquid seal adjacent the faceof the formation, and charge a liquid medium into the tunnel through theseal to pressurize the tunnel about the casing, and to retain theformation about the rod when the casing is retracted from the tunnel.

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GER/41D I 511/55 NE) BY OLIVER 5 mom/v -%zzlwm%wm ATTORNEYS Patented May30, 1972 4 shoots-Shot 5 INVENTORS' JTTOANEY? Patented May 30, 1972 I\ATNU m lull-IIIIIIIII 4 Shoots-Shut 4 INVENTORS" GER/11D T. SWEENEY BYOLIVER E. ERDMA/V ATTORNEYS METHOD AND APPARATUS FOR INSTALLINGELONGATED RODS IN UNSTABLE EARTH FORMATIONS FIELD OF THE INVENTION Thisinvention relates to a means and technique for installing elongated rodsin earth formations, and in particular, to the installation of such rodsin earth formations which are unstable that is, which tend to collapseand fill any excavation which is made in them.

BACKGROUND OF THE INVENTION INCLUDING CERTAIN OBJECTS THEREOF In our US.Pat. No. 3,391,543, we described a means and technique for installingelongated rods in such formations. The principal object of the presentinvention is to provide a means and technique of this nature wherebysuch rods can be installed in earth formations which are so unstable asto tend to collapse and bind or restrain a tunnelling mechanism such asa drill casing inserted therein. Another object is to provide a meansand technique of this nature whereby the rods can be installed withoutshrinking the formation that is, without producing a substantial netexcavation in the formation. A

further object is to provide a means and technique of this nature whichis applicable to the same types of rods listed in out patent, and to thesame distances, directions, weights and strengths of material recited inconnection with these types of rods. Other objects include the provisionof a means and technique of this nature for installing soil anchors inhighly water saturated earth formations below rivers and harbors, aswell as for the installation of drain pipes in water laden sand beds orother aquifers which are so highly saturated as to generate a hydraulicpressure of 25 psi or greater. Still further objects will becomeapparent from the description of the invention which follows hereafter.

SUMMARY OF THE INVENTION These objects and advantages are realized by ameans and technique of our invention wherein, when carrying out ourearlier-technique of installing a tubular casing in a tunnel in a faceof the formation, inserting the rod in the casing, and then retractingthe casing from the tunnel, we install and retract the casing through aliquid seal adjacent the face of the formation, and charge a liquidmedium into the tunnel through the seal to pressurize the tunnel aboutthe casing, and to retain the formation about the rod when the casing isretracted from the tunnel. We may also charge a cure-hardenable liquidmedium into the tunnel through the seal around the rod, after the casingis retracted from the tunnel, to close the mouth of the tunnel about therod.

The casing is in the form of a plurality of sections which areattachable lengthwise thereof, and is installed in successive stagesbetween which the sections are added to the casing while the liquidmedium is charged into the tunnel through the seal around the casing.Otherwise, the liquid medium is normally charged into the tunnel throughthe casing during the installation stages thereof.

The liquid medium charged into the tunnel during the retraction of thecasing may be a cure-hardenable grout which is nondisplaceable by theformation when hardened.

The liquid seal is formed by a tubular device which is sealed to theformation adjacent the face thereof. Where the formation has a layer ofrelatively stable material adjacent the face thereof, the tunnel isnormally excavated through an opening in the layer after the tubulardevice is sealed thereabout. For example, where the formation islaterally supported by sheet metal piling, the opening in the same maybe formed in two progressively radially enlarged stages between which aplug of cure-hardened grout is formed between the opening and the faceof the formation, and a nipple-like sleeve device is installed aroundthe outside of the opening and sealed to the piling. n the other hand,where the formation includes a layer of relatively stable earth materialadjacent the face thereof,

the opening in the same may be formed in two progressivelylongitudinally enlarged stages between which a gland-like sleeve deviceis installed in the opening and sealed to the layer by plugging theannular gap between the opening and the sleeve. The gap may be pluggedby a fluid inflatable bladder on the sleeve; or it may be plugged byinjecting cure-hardenable grout around the sleeve.

In the presently preferred embodiments of the invention, the tubularsealing device has a check-valved fluid inlet therein which communicateswith the passage through the body thereof, for the introduction of theliquid medium into the tunnel therethrough. The device also has apressure relief valve thereon which communicates with .the passage todischarge material excavated from the tunnel.

The device may also have a gate valve therein which is operable to closethe passage through the body thereof at a point between the inlet andthe end of the device through which the casing is introduced into thepassage.

The face of the formation need not be vertically inclined when using ourmeans and technique, but in fact, may be more horizontally inclined,including those situations where the rod must be installed through anoverhead face. Also, the formation need not be unstable because of thewater therein, but in fact, may be constituted by a dry material such assand which nevertheless tends to collapse any excavation which is madein it.

DESCRIPTION OF THE DRAWINGS These features will be better understood byreference to the accompanying drawings which illustrate the invention,firstly, as it is applied to the installation of a soil anchor in awaterbearing earth formation supported by sheet metal piling; andsecondly, as it is applied to the installation of a horizontal drain ina water-bearing formation supported by a facial layer of relativelywater-impervious clay.

In the drawings,

FIG. 1 is a part perspective view of the pile-supported formation,illustrating the first step in a method of forming an opening in thepiling through which the installation procedure can be conducted;

FIG. 2 is a similar view illustrating a second step in the method;

FIG. 3 is a side elevational view of a tractor-mounted version of therod-installing apparatus described in the aforementioned patent, as theapparatus is used in practicing the present invention through theopening in the piling;

FIG. 4 is a part cross-sectional view through the pile-supportedformation after the apparatus has been used to install the casing, and acable for the anchor has been inserted therein;

FIG. 5 is a similar view of the formation at the plane of the piling,illustrating a device for sealing and pressurizing the formation duringthe installation of the casing, as well as the patented means forretracting the casing from the formation;

FIG. 6 is a composite cross-section view of the formation, illustratingthe grouting of the cable and the closing of the opening in the piling;

FIG. 7 is a third part perspective view of the formation after theinstallation procedure has been completed and the opening has beenclosed; and

FIG. 8 is a view similar to that of FIG 5 illustrating the installationof the horizontal drain, and in particular, the sealing device used inthis connection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, itwill be seen that the earth formation 2 in the embodiment in FIGS. 1-7is laterally supported by a system of vertically installed sheet metalpiling 4 which is ribbed or corrugated to give it increased strength. Inorder to tunnel into the formation 2 through the piling 4 without thenecessity for using a combination metal and earth drilling bit on thedrill rod 6, the first step in the over-all operation is to substitute asecondary seal of cure-hardenable grout 8 for a portion 10 of thepiling. The grout 8 is injected into the formation through a small-sizedopening 12 in the portion, and after it has cured, the portion 10 is cutaway or otherwise removed to expose the seal 8. Typically, the removedportion 10 is disc-shaped in configuration as shown, and has a diameterslightly greater than the tunnel 14 to be excavated in the formation.

The tunneling procedure is carried out in the manner described in ourpatent, by using a ported, check-valve-controlled, detachable bit 16which is greater in diameter than the drill rod 6, and by charging wateror other liquid medium through the rod into the tunnel during thedrilling operation to flush the excavated material out through theannular space 18 between the rod and the wall of the tunnel 14. Thedrill rod 6 is assembled in successive stages from lO-foot sections ofsteel tubing 6' which are threaded at their ends to be flush-coupledwith one another into the necessary length of rod. After the tunnel 14is completed, the cable 20 for the anchor is inserted in the rod, agrouting material 22 is charged up the rod about the cable, and then therod is retracted from the tunnel in successive stages, after each ofwhich the section at the end of the rod adjacent the mouth of the tunnelis detached and removed from the rod. Grout is also charged into the rodabout the cable 20 during each retraction stage, as shall be explained.In each case, the grout 22 is charged through, and held in the rod aboutthe cable, by a piston device 24 which is advanced from one end section6' to the next during each retraction stage, and locked in the lattersection between stages while the one end section is detached and removedfrom the rod.

In earth formations 2 having a high hydrostatic head, such aswater-bearing sand formations below the surface of a river or harbor, itmay also be necessary to pressurize the tunnel about the rod, during theentire operation. This is particularly true where the operation must beconducted without producing a substantial net shrinkage in theformation, as for example, where construction work in the area dependson a stabilized earth condition thereabout. Accordingly, in such cases,the tunnel 14 is sealed and pressurized during the installationprocedure by the means and technique illustrated in FIGS. 3, and 6.

Referring to these figures, it will be seen that a nipple-like sealingdevice 26 is bolted to the face of the piling 4 about the disc-shapedopening 28 therein, using bolts 29 which are welded to the face of thepiling in a circle about the opening. The sealing device 26 includes apair of coaxial sleeves 30 and 32, the adjacent ends of which areflanged and bolted to a hand-operated gate valve 34 interposedtherebetween. The sleeves are adapted to have the drill rod 6 installedtherethrough, when the valve 34 is open, and since the operation isgenerally conducted at an angle to the face of the piling, the leadingend portion of the forward sleeve 32 is truncated at such angle, and theend itself is equipped with an annular flange 36 having a suitablyspaced number of apertures therein to enable the device to be securedover the bolts 29 with an elastomeric sealing ring 38 interposedtherebetween. In addition, the trailing end portion of the rearwardsleeve 30 is equipped with an elastomeric packing gland 40 which isadapted to constrict about the drill rod 6 during the operation byreason of its interposition between an annular rib 42 in the sleeve 30and a compression cap 44 which is threaded into the trailing end of thesame about the rod. Thus, the device 26 is adapted to maintain a liquidseal between the piling and the rod as water is charged into the tunnelthrough the rod; so that the charge operates to pressurize the tunnelabout the rod during the operation.

Between each drilling stage, however, when the drillstock 46 of therod-installing apparatus 48 is disconnected from the rod 6 to enable theaddition of another section 6' to the same, it is necessary to maintainthe pressure in the tunnel by other means. Thus, the tunnel is chargedwith additional liquid medium through the sealing device 26 itself; andfor this purpose, the forward sleeve 32 of the device is equipped with atee 50 having a check-valved fluid inlet 52 threaded therein which isfed throughout the operation by a small hydraulic pump (not shown) tomaintain a preset pressure in the tunnel. The pump operates inconjunction with a heavy duty pressure relief valve 54 on the device,which not only regulates the pressure in the tunnel, but also dischargesthe excavated material to the outside as the tunneling operationproceeds. The pressure relief valve 54 is housed in another tee 56 onthe forward sleeve, and is equipped with a gate valve 58 on one sidethereof, the function of which will be explained shortly.

Typically a pressure of ten psi or greater, above that of the formation,is maintained in the tunnel by the setting of the pressure relief valve.

To form the head 60 of the anchor, the grouting material which ischarged into the forward end of the tunnel ahead of the piston, has alow shrinkage and high compression strength. Thereafter, however, as thedrill rod is being retracted, the grouting material is reduced to a weaklime and cement mixture 62 so as to back-fill the tunnel 14 with amaterial which has a high shrinkability, yet is capable of preventingsubstantial shrinkage in the formation 2.

The inlet 52 may also be used to pressurize the tunnel dur ing theretraction process, although this is generally unnecessary wheninstalling soil anchors. In any event, however, it is usually necessaryto close the opening 28 in the piling after the last section of rod hasbeen retracted therefrom, and the inlet is used for this purpose. Asseen in FIG. 5, the cable 20 is measured and cut to a length designed toterminate it at a point between the sleeve gate valve 34 and the piling.When the last section of rod has been withdrawn behind or to the left ofthe gate valve, both it and the gate valve 58 in conjunction with thepressure relief valve, are closed, and a high-compressionstrength,low-shrinkability grouting material 64 is injected into the openingthrough the inlet 52. See FIG. 6. Thus, when the grouting 64 is hard andthe sealing device 26 is removed, the opening 28 is effectively pluggedby the same, although enough of the cable 20 remains exposed, or issubsequently exposed, to enable it to be connected to the piling. SeeFIG. 7. The bolts 29 may also be removed.

In the embodiment of FIG. 8, a water laden sand formation 66 islaterally supported by a natural embankment 68 of clay or the like whichmust be penetrated to release the water through a horizontal drain 70.Moreover, if the operation is to be successful, it is necessary, as inthe earlier embodiment, to seal and pressurize the formation during theinstallation of the drain. Thus, the operation is again carried outthrough a sealing device, which in this instance, however, is insertedin the water impervious material to form a gland-like seal 72 betweenthe casing 6 and the material. The device 72 comprises a pair of coaxialsleeves 74 and 76 which are coupled together by a standard femalecoupling 78 to a combined length of ten feet. The rearward sleeve 76 notonly has a packing 80 and compression cap 82 associated therewith, as inthe earlier embodiment; but is also equipped with a checkvalved fluidinlet 84 and a gate-valved pressure relief valve 86, that are similar tothose on forward sleeve 30 in the earlier embodiment. The pressurerelief valve 86 is on the discharge side of the gate valve 88 in thisinstance, however, for ease of cleaning; and is cooperable with aslotted opening 90 in the housing 92 for the same.

The device 72 operates to form a seal between the water imperviousmaterial and the rod 6, by means of a flexible rubber bladder 94 whichis annular in shape and installed about the last three feet of theforward sleeve 74 for insertion in the embankment. The circumferentialedges of the bladder are vulcanized to the sleeve to form an envelope 96which can be inflated through a tube 98 that is extendible from thebladder to a point outside of the embankment. At the start of theoperation, a 10-foot long hole 100 which is slightly larger in diame terthan the sleeve is augered out of the embankment; and after the sleeveis inserted in the hole with the bladder thereon, either water, oil, orair is introduced into the bladder to inflate the same until it forms asnug packing gland between the sleeve and the wall of the hole.Thereafter, the operation is conducted in the same manner as the earlierembodiment, although for the purposes of a drain, a water medium is usedthrough the operation. After the rod and device are removed, however,grouting is applied to the mouth of the opening in the embankment, aboutthe drain, to seal off the annular space therebetween.

Alternatively, an elongated pipe may be. grouted or otherwise cementedinto the water impervious stratum of the embankment, to form a sealinggland.

Also, where the embankment has considerable height above the mouth ofthe tunnel, it may be practical to use elevational head, rather than apump head, to pressurize the tunnel, as for example, where the liquidtailings which escape from the sealing device during the excavationprocess are raised and stored at a point above the mouth of the tunnelfor this purpose.

Similarly, one can subject the invention to many other modifications andadditions without departing from the scope and spirit of the same asdefined in the claims following.

What is claimed is:

1. 1n the process of installing an elongated rod in an earth formationby the steps of installing a tubular casing in a tunnel in a face of theformation, inserting the rod in the casing, and then retracting thecasing from the tunnel, the improvement comprising the steps ofinstalling and retracting the casing through a liquid seal adjacent theface of the formation, and charging a liquid medium into the tunnelthrough the seal to pressurize the tunnelabout the casing, and to retainthe formation about the rod when the casing is retracted from thetunnel.

2. The process according to claim 1 further comprising charging acure-hardenable liquid medium into the tunnel through the seal aroundthe rod, after the casing is retracted from the tunnel, to close themouth of the tunnel about the rod.

3. The process according to claim 1 wherein the casing is in the form ofa plurality of sections which are attachable lengthwise thereof, and isinstalled in successive stages between which the sections are added tothe casing while the liquid medium is charged into the tunnel throughthe seal around the casing.

4. The process according to claim 3 wherein the liquid medium is chargedinto the tunnel through the casing during the installation stagesthereof.

5. The process according to claim 3 wherein the liquid medium chargedinto the tunnel during the retraction of the casing is a cure-hardenablegrout which is non-displaceable by the formation when hardened. v

6. The process according to claim 1 wherein the liquid seal is formed bya tubular device which is sealed to the formation adjacent the facethereof.

7. The process according to claim 6 wherein the formation has a layer ofrelatively stable material adjacent the face thereof, and the tunnel isexcavated through an opening in the layer after the tubular device issealed thereabout.

,8. The process according to claim 7 wherein the opening in the layer isformed in two progressively radially enlarged stages between which aplug of cure-hardened grout is formed between the opening and the faceof the formation, and a nipple-like sleeve device is installed aroundthe outside of the opening and sealed to the layer.

9. The process according to claim 7 wherein the opening in the layer isformed in two progressively longitudinally enlarged stages between whicha gland-like sleeve device is installed in the opening and sealed to thelayer by plugging the annular gap between the opening and the sleeve.

10. The process according to claim 9 wherein the gap is plugged by afluid inflatable bladder on the sleeve-like device.

11. In apparatus for installing an elongated rod in an earth formationby the steps of installing a tubular casing in a tunnel in a face of theformation, inserting a rod in the casing, and then retracting the casingfrom the tunnel, the improvement comprising means for formingla liquidseal ad'acent the face of the formation through WhlC the casing can einstalled and retracted, and means for charging a liquid medium into thetunnel through the seal to pressurize the tunnel about the easing, andto retain the formation about the rod when the casing is retracted fromthe tunnel.

12. The apparatus according to claim 11 wherein the latter means areadapted to charge the liquid through the seal around the casing.

13. The apparatus according to claim 11 wherein the liquid seal formingmeans includes a tubular device which is adapted to be sealed to theformation adjacent the face thereof.

14. The apparatus according to claim 13 wherein the tubular deviceincludes a nipple-like sleeve device which is adapted to be installedaround an opening in a layer of relatively stable material adjacent theface of the formation, through which the tunnel is excavated.

15. The apparatus according to claim 13 wherein the tubular deviceincludes a gland-like sleeve device which is adapted to be installed inan opening in a layer of relatively stable earth material adjacent theface of the formation, through which the tunnel is excavated.

16. The apparatus according to claim 15 wherein the sleevelike devicehas a fluid inflatable bladder formed thereon.

17. The apparatus according to claim 13 wherein the tubular device has acheck-valved fluid inlet therein which communicates with the passagethrough the body thereof, for the introduction of the liquid medium intothe tunnel therethrough.

18. The apparatus according to claim 17 wherein the tubular device alsohas a pressure relief valve thereon which communicates with the passageto discharge material excavated from the tunnel.

19. The apparatus according to claim 17 wherein the tubular device alsohas a gate valve therein which is operable to close the passage at apoint between the inlet and the end of the device through which thecasing is introduced into the passage.

1. In the process of installing an elongated rod in an earth formationby the steps of installing a tubular casing in a tunnel in a face of theformation, inserting the rod in the casing, and then retracting thecasing from the tunnel, the improvement comprising the steps ofinstalling and retracting the casing through a liquid seal adjacent theface of the formation, and charging a liquid medium into the tunnelthrough the seal to pressurize the tunnel about the casing, and toretain the formation about the rod when the casing is retracted from thetunnel.
 2. The process according to claim 1 further comprising charginga cure-hardenable liquid medium into the tunnel through the seal aroundthe rod, after the casing is retracted from the tunnel, to close themouth of the tunnel about the rod.
 3. The process according to claim 1wherein the casing is in the form of a plurality of sections which areattachable lengthwise thereof, and is installed in successive stagesbetween which the sections are added to the casing while the liquidmedium is charged into the tunnel through the seal around the casing. 4.The process according to claim 3 wherein the liquid medium is chargedinto the tunnel through the casing during the installatioN stagesthereof.
 5. The process according to claim 3 wherein the liquid mediumcharged into the tunnel during the retraction of the casing is acure-hardenable grout which is non-displaceable by the formation whenhardened.
 6. The process according to claim 1 wherein the liquid seal isformed by a tubular device which is sealed to the formation adjacent theface thereof.
 7. The process according to claim 6 wherein the formationhas a layer of relatively stable material adjacent the face thereof, andthe tunnel is excavated through an opening in the layer after thetubular device is sealed thereabout.
 8. The process according to claim 7wherein the opening in the layer is formed in two progressively radiallyenlarged stages between which a plug of cure-hardened grout is formedbetween the opening and the face of the formation, and a nipple-likesleeve device is installed around the outside of the opening and sealedto the layer.
 9. The process according to claim 7 wherein the opening inthe layer is formed in two progressively longitudinally enlarged stagesbetween which a gland-like sleeve device is installed in the opening andsealed to the layer by plugging the annular gap between the opening andthe sleeve.
 10. The process according to claim 9 wherein the gap isplugged by a fluid inflatable bladder on the sleeve-like device.
 11. Inapparatus for installing an elongated rod in an earth formation by thesteps of installing a tubular casing in a tunnel in a face of theformation, inserting a rod in the casing, and then retracting the casingfrom the tunnel, the improvement comprising means for forming a liquidseal adjacent the face of the formation through which the casing can beinstalled and retracted, and means for charging a liquid medium into thetunnel through the seal to pressurize the tunnel about the casing, andto retain the formation about the rod when the casing is retracted fromthe tunnel.
 12. The apparatus according to claim 11 wherein the lattermeans are adapted to charge the liquid through the seal around thecasing.
 13. The apparatus according to claim 11 wherein the liquid sealforming means includes a tubular device which is adapted to be sealed tothe formation adjacent the face thereof.
 14. The apparatus according toclaim 13 wherein the tubular device includes a nipple-like sleeve devicewhich is adapted to be installed around an opening in a layer ofrelatively stable material adjacent the face of the formation, throughwhich the tunnel is excavated.
 15. The apparatus according to claim 13wherein the tubular device includes a gland-like sleeve device which isadapted to be installed in an opening in a layer of relatively stableearth material adjacent the face of the formation, through which thetunnel is excavated.
 16. The apparatus according to claim 15 wherein thesleeve-like device has a fluid inflatable bladder formed thereon. 17.The apparatus according to claim 13 wherein the tubular device has acheck-valved fluid inlet therein which communicates with the passagethrough the body thereof, for the introduction of the liquid medium intothe tunnel therethrough.
 18. The apparatus according to claim 17 whereinthe tubular device also has a pressure relief valve thereon whichcommunicates with the passage to discharge material excavated from thetunnel.
 19. The apparatus according to claim 17 wherein the tubulardevice also has a gate valve therein which is operable to close thepassage at a point between the inlet and the end of the device throughwhich the casing is introduced into the passage.